1. Field of the Invention
The present invention relates to a process for producing a polymer of a vinyl compound having a bulky substituent.
2. Description of Related Art
In the field of polymerization of olefins such as polyethylene and polypropylene, a development in which a polymer different in properties from ordinary polymers can be produced has been done by appearance of single-site catalyst such as so-called metallocene and non-metallocene catalysts.
With respect to polymerization of a vinyl compound having a bulky substituent such as vinylcyclohexane, application of such a catalyst is proposed, and for example, processes for producing copolymers of ethylene and vinylcyclohexane are disclosed in Polymer Science USSR, Vol.32, No.9, 1868-1872(1990), and Polymer, vol.134(9), 1941(1993).
Such a polymer of the vinyl compound having a bulky substituent exhibits similar properties to polyvinyl chloride, therefore are expected as non-chlorine materials. However, in the known process, the copolymerizability of the vinyl compound having a bulky substituent used is low (namely, the ratio of units derived from the vinyl compound having a bulky substituent contained in a obtained polymer is rather low compared to the ratio of the vinyl compound fed in polymerization). Therefore, it was difficult to obtain efficiently a copolymer having high ratio of the units derived from the vinyl compound having a bulky substituent, further also to obtain a homopolymer of the vinyl compound having a bulky substituent.
An object of the present invention is to provide a process for producing efficiently a homopolymer of the vinyl compound having a bulky substituent or a copolymer containing units derived from the vinyl compound having a bulky substituent with a good copolymerizability.
Namely, the present invention relates to a process for producing a polymer which comprises polymerizing a vinyl compound (I) represented by the general formula CH2xe2x95x90CHxe2x80x94R, wherein steric parameters Es and B1 of the substituent R are respectively xe2x88x921.64 or less and 1.53 or more or a vinyl compound (II) represented by the general formula CH2xe2x95x90CHxe2x80x94Rxe2x80x2, wherein a substituent Rxe2x80x2 is a secondary or tertiary alkyl group, in the presence of a catalyst obtained by combining:
(A) a transition metal compound represented by the general formula [1]
wherein M represents a transition metal; each of Cp1 and Cp2 independently cyclopentadiene type anion skeleton; each of R1 and R2 independently represents a hydrogen atom or hydrocarbon group having 1 to 20 carbon atoms, and they may connect and form a ring structure through C; X represents a halogen atom, hydrocarbon group having 1 to 20 carbon atoms or hetero atom; and n represents a number of 0 to 4;
(B) at least one aluminum compound selected from the following (B1) to (B3):
(B1) an organoaluminum compound represented by the general formula E1aAlZ3xe2x88x92a,
(B2) a cyclic aluminoxane having a structure represented by the general formula {xe2x80x94Al(E2)xe2x80x94Oxe2x80x94}b, and
(B3) a linear aluminoxane having a structure represented by the general formula E3{xe2x80x94Al(E3)xe2x80x94Oxe2x80x94}cAlE32,
(wherein E1 to E3 respectively represents a hydrocarbon group having 1 to 8 carbon atoms, and all of E1, E2 and E3 may be the same or different; Z represents a hydrogen atom or a halogen atom, and all of Z may be the same or different; a represents a numeral satisfying 0 less than axe2x89xa63; b represents an integer of not less than 2; and c represents an integer of not less than 1); and
(C) at least one boron compound selected from the following (C1) to (C3):
(C1) a boron compound represented by the general formula BQ1Q2Q3,
(C2) a boron compound represented by the general formula G+(BQ1Q2Q3Q4)31, and
(C3) a boron compound represented by the general formula (Lxe2x80x94H)+(BQ1Q2Q3Q4)xe2x88x92
(wherein B is a boron atom in the trivalent valence state, Q1 -Q4 are a halogen atom, a hydrocarbon group, a halogenated hydrocarbon group, a substituted silyl group, an alkoxy group or a di-substituted amino group, which may be the same or different, respectively. G+ is an inorganic or organic cation, L is a neutral Lewis base, and (Lxe2x80x94H)+ is a Brxcfx86nsted acid.)